I am looking at a portable generator for my 5th wheel. It can generate 3500 watts/23 Amps on a 4 prong circular twist lock plug which is rated 124/240 volts AC. I need to make a converter extension cord to change the 4 prong 240 to a 3 prong 120 outlet.(Plug needs a to able to plug in a mobile home which runs on 120 volts). If I understand correctly, the 4 prong plug has 2-120 volt lines, a neutral line and a ground line. Is it as simple as picking up one the 120 lines, the neutral line and the ground line to make the conversion?

Hi,
The plug is basically a neutral line in the middle of two 120V lines, one is on the positve side of the neutral and the other on the negative side. Then there is the ground. The conventional color code would be black - 120V, red - 120V, white - neutral, and green - ground. You may not have the full amperage available with only half the system.
Peace,
Clarke

It might be easier to buy the adaptor. I think this is the one you need. You can get it for $39.99 at Camping World.

Power Grip 30-Amp Generator Adapter - Item - Camping World